1. Field of the Invention
The present invention relates generally to remote control systems, and specifically to a transmitter or transceiver that is programmable and capable of operating multiple devices by transmitting multiple codes at multiple frequencies, using multiple transmission formats.
2. Background of the Invention
Transmitter-receiver controller systems are widely used for remote control and/or actuation of devices or appliances such as garage door openers, gate openers, security systems, and the like. For example, most conventional garage door opener systems use a transmitter-receiver combination to selectively activate the drive source (i.e., motor) for opening or closing the door. The receiver is usually mounted adjacent to the motor and receives a coded signal (typically radio frequency) from the transmitter. The transmitter is typically carried by a user and selectively activated by the user to open or close the garage door. These type of remote control systems typically employ VHF/UHF radio frequency transmissions.
In general, a remote control system has a remote transmitter and a receiver coupled to the device, which is to be controlled. When activated, the transmitter emits a modulated signal, which is recognized by the receiver to activate the device. In VHF/UHF-based systems, a transmitter typically emits a pulse-modulated VHF/UHF signal. The signal embodies a modulation pattern as a sequence of “signal on” and “signal off” intervals. The modulated signal emitted by the transmitter is recognized by the receiver. The modulation pattern of remote control systems is typically unique to restrict unauthorized access to the device being controlled.
Alternatively, the modulation pattern may be comprised of a rolling code signal which changes for each transmission, as a function of a predetermined algorithm. Each new rolling code is generated using a rolling code generator, where both the transmitter and its corresponding receiver will contain the same rolling code generator. In such systems, the receiver will only be activated if it receives one of a limited number of possible rolling codes from the transmitter. Since both the transmitter and the receiver are advancing through a rolling code sequence using the same rolling code engine, the transmitter will typically be able to provide an acceptable code to the receiver.